The present invention relates to an improved spring strut of a motor vehicle having a bearing for a coil spring with elastic spring supports received by supporting elements, on which spring supports the coil spring is supported. A spring supporting surface on at least one of the elastic spring supports extends in a sloped manner corresponding to a pitch of the spring and has an elasticity which is the same in a supporting area of the spring.
European Patent Document EP 0 564 824 B1 relates to a bearing on a vehicle body for a spring strut of a motor vehicle. This bearing has a spring plate holding an elastic support, and a coil spring is supported on the spring plate. The elastic support has a spring supporting surface extending in a sloped manner corresponding to the pitch of the spring and an elasticity which is the same in the supporting area of the spring. For achieving the same elasticity in the upper supporting area of the spring, a spacing element which engages by way of shaped-out areas in the spring element is provided. The effective resilient area, in each case, has a uniform spacing along the circumference of the spring.
It is an object of the invention to provide a spring strut with an improved bearing for a spring by which buckling of the coil spring is avoided during cushioning operations. In addition, stress concentrations on the spring plate are to be prevented. Furthermore, it should be possible to easily use springs of different lengths.
According to certain embodiments of the invention, this object is achieved by configuring the spring strut such that free ends of the spring are supported by way of elastic spring supports held in the supporting elements. One of the elastic spring supports is held in one of the supporting elements on the vehicle body and the other of the elastic supports is held in the other of the supporting elements at a shock absorber tube. Twist fixations, by way of which the supporting elements are in mutual engagement with corresponding ones of said spring supports, are provided. The spring supports are resiliently constructed in the area of these fixations. A spring plate carries the supporting element and the spring support. The spring plate is detachably connected with a shock absorber tube of the spring strut and is supported, on the shock absorber tube, on bearings.
Additional advantageous characteristics are also reflected in the claims.
The principal advantages achieved by the invention are that, as a result of the construction and corresponding arrangement of the supporting element with the spring support, on the one hand, no buckling of the spring will occur during dynamic operations and, on the other hand, the spring support cannot rotate in the supporting element. As a result, no change in the supporting position of the spring with respect to the spring plate takes place. For this purpose, each free end of the spring is supported by way of the elastic spring support held in a supporting element, on the one hand, on the vehicle body and, on the other hand, on the shock absorber tube. The supporting elements are in a mutual engagement with the spring supports by way of twist fixations, and the spring support has a resilient construction in this fixing area.
A form-locking connection between the supporting element and the spring support takes place by way of two spaced teeth in the supporting element which engage in a corresponding recess in the spring support. A clearance exists between the two teeth, and the lateral boundary flanks of the recess adjoin outer flanks of the teeth in a form-locking manner. This prevents mutual rotatability.
So that, despite the twist fixation, the same elastic effect can take place along the entire winding, the lower free end of the spring ends directly next to the boundary surface, and the spring winding above and in the area of the recess is released from the guide groove of the spring support. For this purpose, the spring support has a supporting surface corresponding to the angle of the spring winding which is constructed parallel to a supporting surface on the supporting element to the twist fixation and is constructed along the entire circumference with approximately the same stiffness and the same thickness.
In order to prevent the elastic spring support from being crushed during dynamic load conditions, and so that the stiffness is not advantageously changed, the lower supporting element can be a pot-shaped part with a bent-up edge. As a result, the edge reaches partly around the spring support. The edge is interrupted only in the area of the teeth, so that no additional friction occurs in this area and an unhindered spring effect can occur. The upper bearing plate receives the supporting element and the spring support, also has a pot-shaped construction, and reaches around the supporting element and the spring support in a spaced manner.
The elastic spring supports are formed of rubber or a similar material, and the supporting element is formed of plastic or a light metal. The spring plate may be formed of aluminum or steel.
So that the distance between the vehicle-body-side support and the lower spring plate can be varied, the spring plate can be fitted onto the shock absorber tube and rotated such that the spring plate can be adjusted at different levels on the shock absorber strut. The spring plate has a plurality of recesses on its interior circumferential surface for this purpose, and these recesses are distributed along the circumference. At least three recesses have the same depth, and the additional recesses have a different depth.
Embodiments of the invention are illustrated in the drawings and will be described in detail.